1. Technical Field
The present invention relates a device and method for driving a developing unit in an image forming apparatus, and more particularly to the image forming apparatus such as an electrophotographic copying machine or a printer having a detachable and programmable developer cartridge capable of preventing unauthorized usage of the developer cartridge in the image forming apparatus.
2. Background Art
Conventionally, the image forming apparatus such as an electrophotographic copying machine, facsimile machine or printer includes means for preventing a person other than the authorized users from using the image forming apparatus. For example, in U.S. Pat. No. 5,300,761 for Image Forming Apparatus Counting System Using Individual And Collective Counters, Kasahara et al. employ a registering device for registering a plurality of identification codes and a comparing device for comparing the authorized user's pre-assigned identification code stored in a detachable and portable memory CARD with the plurality of identification codes registered in the registering device so as to enable the authorized user to operate the image forming apparatus. Similarly, in European Patent No. 0 589 130 A2 for Image Forming Apparatus Using ID Card Having Counter, Ogura uses a memory CARD for storing the user's ID code so as to enable the user to access the copier when the user's identification code matches a predetermined identification code registered in the copier.
The image forming apparatus described in Japanese Patent Publication Nos. 2-73284 and 60-113164 issued to Ishii and Osako however requires the user to directly enter his own identification code for a match with a registered identification code prior to operating the copier. Specifically, in Japanese Patent Publication No. 2-73284, Ishii requires the user to directly enter his pre-assigned identification code into the copier so that the copier could compare the user's entered identification code with a registered identification code in order to release the copy inhibition mode. In Japanese Patent Publication No. 60-113164, Osako further requires the user to reserve his own identification code in the copier before he could release the operation stop state for copying. In the event if the user does not reserve his own identification code in the copier, however, the use of the copier is prohibited.
Another unauthorized access prevention technique is disclosed in U.S. Pat. No. 5,270,773 for Image Producing Device With Security To Prevent Disclosure of Sensitive Documents issued to Sklut et al. In Sklut '773, an operator password login system is used in conjunction with an image forming apparatus where access to machine copy functions is prohibited until an appropriate operator password has been entered and validated.
In these unauthorized access prevention schemes, however, the objective is to prevent unauthorized users from operating the image forming apparatus. It has been my observation that none of these efforts accommodate security to the individual articles of consumption within the image forming apparatus themselves such as, for example, a developing unit, a photosensitive drum unit, a toner, etc., all of which are detachable and exchangeable upon depletion because of continuous and repeated uses.
For example, commercial developing units typically have different prices depending upon the printing resolution such as 300 dpi or 600 dpi, or dependent upon whether they are used in conjunction with high quality toner or general toner. Consequently, if the user has the developing unit comprising high quality toner with high resolution of 600 dpi, he would want to control the usage of the developing unit in order to conserve the life of the developing unit and reduce cost. The user would therefore appreciate the necessity of controlling the usage of the developing unit,in order for example, to prevent an unauthorized person from using his own developing unit. Such necessity would further be appreciated by commercial manufacturers who manufacture their own models of image forming apparatus using particular types of developing units. In a conventional image forming apparatus, if an unauthorized person uses different models of developing units without permission of its owner, the image forming apparatus itself could be damaged and the printing quality could be deteriorated. Consequently, operation of the image forming apparatus becomes unreliable, and damages would inevitably arise whenever exchangeable parts having limited life spans, such as a toner hopper, a developing unit, a photosensitive drum unit are used in the image forming apparatus.